Bump github.com/cloudevents/sdk-go/v2

Bumps [github.com/cloudevents/sdk-go/v2](https://github.com/cloudevents/sdk-go) from 2.13.0 to 2.15.2.
- [Release notes](https://github.com/cloudevents/sdk-go/releases)
- [Commits](cloudevents/sdk-go@v2.13.0...v2.15.2)

---
updated-dependencies:
- dependency-name: github.com/cloudevents/sdk-go/v2
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

e2e-test-server/cloud_functions/go.mod

@@ -6,7 +6,7 @@ require (
 	cloud.google.com/go/pubsub v1.33.0
 	github.com/GoogleCloudPlatform/functions-framework-go v1.6.1
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/e2e-test-server v0.46.0
-	github.com/cloudevents/sdk-go/v2 v2.13.0
+	github.com/cloudevents/sdk-go/v2 v2.15.2
 )
 
 require (

e2e-test-server/cloud_functions/go.sum

@@ -75,8 +75,8 @@ github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5P
 github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/cloudevents/sdk-go/v2 v2.6.1/go.mod h1:nlXhgFkf0uTopxmRXalyMwS2LG70cRGPrxzmjJgSG0U=
-github.com/cloudevents/sdk-go/v2 v2.13.0 h1:2zxDS8RyY1/wVPULGGbdgniGXSzLaRJVl136fLXGsYw=
-github.com/cloudevents/sdk-go/v2 v2.13.0/go.mod h1:xDmKfzNjM8gBvjaF8ijFjM1VYOVUEeUfapHMUX1T5To=
+github.com/cloudevents/sdk-go/v2 v2.15.2 h1:54+I5xQEnI73RBhWHxbI1XJcqOFOVJN85vb41+8mHUc=
+github.com/cloudevents/sdk-go/v2 v2.15.2/go.mod h1:lL7kSWAE/V8VI4Wh0jbL2v/jvqsm6tjmaQBSvxcv4uE=
 github.com/cncf/udpa/go v0.0.0-20191209042840-269d4d468f6f/go.mod h1:M8M6+tZqaGXZJjfX53e64911xZQV5JYwmTeXPW+k8Sc=
 github.com/cncf/udpa/go v0.0.0-20200629203442-efcf912fb354/go.mod h1:WmhPx2Nbnhtbo57+VJT5O0JRkEi1Wbu0z5j0R8u5Hbk=
 github.com/cncf/udpa/go v0.0.0-20201120205902-5459f2c99403/go.mod h1:WmhPx2Nbnhtbo57+VJT5O0JRkEi1Wbu0z5j0R8u5Hbk=